1. Field of the Invention
This invention is concerned with a process of recovering copper from various copper salts by means of hydrogen reduction at temperatures exceeding the melting point of copper.
2. The Prior Art
Many processes have been taught for the hydrogen reduction of metallic salts to recover the elemental metal. For example, U.S. Pat. No. 2,111,661 to Ebner discloses the passing of finely divided molten magnesium chloride through a reaction chamber of hydrogen gas at a temperature of 1200.degree. C. to 1500.degree. C. in order to reduce the magnesium chloride to magnesium. Thereafter, the magnesium is recovered by condensation.
Several techniques deal specifically with copper salts. Baghdasarian in U.S. Pat. No. 1,671,003 discloses chlorinating metallic sulfides at temperatures in the range of 900.degree. to 1200.degree. C. to their corresponding metallic chlorides, and then reducing the metallic chlorides with hydrogen to produce the elemental metal and hydrogen chloride. The preferred temperature disclosed for reducing lead chloride with hydrogen is in excess of 800.degree. C.; whereas, a lower temperature is taught to be preferable for the reduction of copper chlorides.
Additionally, a cyclone reaction chamber has been used in a smelting process for impure copper concentrates. "The KIVCET Cyclone Smelting Process for Impure Copper Concentrates" Journal of Metals, July, 1976, page 4, teaches the oxidation and slagging of the copper in a cyclone with the reduction of copper occurring in the settling hearth at temperatures of about 1350.degree. to 1400.degree. C.
Many of these processes have problems with the reduced copper agglomerating and sintering. U.S. Pat. No. 4,039,324 to Stephens, Jr. et al circumvents this problem by reducing the copper salts with hydrogen at a temperature of from about 200.degree. to about 1000.degree. C. in a fluidized bed in the presence of chemically inert, generally spherical, relatively smooth, non-porous particles.
However, none of the prior art teaches the hydrogen reduction of solid copper bearing material at a temperature greater than the melting point of copper under conditions which result in substantially instantaneous copper reduction coupled with efficient fume collection.